Voltage regulator



Patented Feb. 15,1949

UNITED STATES PATENT OFFICE 3 Claims.

(Granted under the act of March 3,

-- amended April-a0, 1928; :70 o. G. mi

1 The invention described herein may be manufactured and used by or for the Government for governmental purposes, without the payment to me of any royalty thereon.

This invention relates to voltage regulators and more particularly to a voltage regulator for use in supplying very high voltages.

There are many needs in electronic circuits for a source of constant voltage. There are in existence several types of circuits to provide such a voltage most of which use vacuum tubes in degenerative amplifier form when a very accurate stabilization is required. A less stable type of regulator is one using a gas discharge diode. For

is provided a voltage regulator of degenerative amplifier'design wherein a separate regulator system replaces the usual series of gas regulator tubes and wherein three tubes replace ten tubes correspondingly disposed in older forms 01' voltage regulators. The present device is capable of regulating very high voltages and is of particular value due to the method used in stabilizing the cathode voltage of an ordinary degenerative amplifier type of regulator by providing a transconductance bridge regulator in place of a series of voltage regulator tubes.

For a better understanding of the invention,

together with other and further objects thereof,

reference is had to the following description, taken in connection with the accompanying drawing. The scope of the present invention will be pointed out in the appended claims.

In the accompanying drawing, the only figure is a circuit diagram of a voltage regulator that embodies the present invention.

Referring now more particularly to the drawing, there is shown schematically a usual 115 volt alternating current power line comprising wires and 36 that supply power to a usual type of rectifier 31. a

The positive conductor 38 from the rectifier 31 is connected to regulator vacuum tubes 49, 50 and 5| as shown. The negative conductor 39 from the rectifier 31 is applied to a transconductance bridge regulator 48 and emerges therefrom as the negative voltage output terminal 40.

A plurality of series connected resistors H, 42,

-43, 44 and 45 are disposed in series across the direct current input connectors 38 and 35. Illustrative values of these resistors are: resistor 4| at 75,000 ohms; resistors 42 and 44 at 10,000 ohms each; resistor 45 at 15,000 ohms; and resistor 43 at 100,000 ohms.

The regulator tube 49 is connected in parallel with the two other regulator tubes 50 and 5| of the type 801, for example, with their plates connected in common to the positive direct current connector 38. The cathodes of the tubes 49, 50 and 5!, are connected in common to a voltage regulator positive output terminal 52. The grids of the regulator tubes 48, 5|! and 5| are connected together and to the plate 53 of a control tube 55 of the type 6SJ7, for example. A resistor 55 joins the connector 38 to the grids of the tubes 49, 50 and Si and also to the plate 53 of the control tube 55 that is believed to function as a feed-back amplifier tube. An illustrative resistor 58 has the value, for example, of 1 megohm. The cathode 51 of the control tube 55 passes its output to the plate 58 of a tube 59 which forms a part of a transconductance bridge regulator 48, shown in dash outline. A suppressor grid 60 of the control tube 55 is connected with and is at the same potential as the cathode 51 of the tube 55. A resistor ii of, for example 5,000 ohms, is interposed between the Junction of the connections to the cathode 51 and the plate 58 and the junction of the resistors 42 and 43. The bias voltage on the screen grid 62 of the control tube 55 is adjustable by the disposition of a potentiometer tap 63 which connects the grid 62 to the potentiometer resistor 42. The bias voltage applied to the control grid 55 of the tube 55 is similarly adjustable by the disposition of a potentiometer tap 66 upon a potentiometer resistor 61 with a protective resistor 88 interposed between the control grid 55 and the tap 55. The resistor 51, in series with resistors 10 and H, is disposed across the output line comprising the terminals 45 and 52 of the voltage regulator. The bias voltage applied to the grid 12 of the tube 59 is controlled by the disposition of a potentiometer tap 13 by which the grid 12 is connected to the potentiometer resistor 44. Illustrative values for resistors 10 and H and potentiometer 61 are 300,000 ohms, 250,000 ohms and 50,000 ohms respectively. The cathode 15 of the tube 59 is connected with the anode 15 of a voltage regulator tube I1 which is in series with another voltage regulator tube of the same type, the cathode 8! of which is connected with the conductor 39. To complete the series connection between the tubes I1 and 80, the cathode 82 of the tube 11 is connected with the anode 83 of the tube 80. Tubes 11 and 80 are of the common gas-fllled diode type.

Referring now to the operation. of the system, the rectifi r 81 functions to rectify the altemating curr t received over the input line wires 85 and 88. The voltage regulator tubes "and 80 its original value. i

Due to the connection of cathode 'I5 to the ne ative bus 59 through the voltage regulators TI and 80, the voltage or cathode I5 remains con-.

stant with reference to bus 88 in spite of variations of applied volt e across the busses 38 and 89. Accordingly increase of voltage at bus 88 will cause an increase in voltage applied to grid" with respect to the voltage of cathode 15. As the plate current in tube 59 increases with increase of grid voltage, the voltage increase on bus 38 is reflected in an amplified increase in plate current in tube 59. This plate current flows chiefly through resistor 5|; so that the voltage drop across resistor 6| shows an increase. By properly proportioning the resistors of transconductance bridge 48 it is possible to absorb the whole increase in voltage input to transconductance a bridge 48 in the drop across resistor 5| so that plate 58 of tube 59 remains at constant voltage with reference to negative terminal 39.

Passing now to tube 55 it is seen that its cathode 51 connected to plate 58 of tube 59 also remains at constant voltage. The grid 55 of'tube 55 is connected to an intermediate point 86 in the series of resistors 10, 61, II placed across the output side or the voltage regulator, that is, between terminals 4|! and 52. Any tendency of the output voltage across terminals 40 and 52 to increase causes a corresponding increase of the voltage of point 85 and of voltage of grid 85 of tube 55. This causes increased conductance of tube55, and accordingly an increase of current through resistor 56. This is sufficient to reduce the voltage of plate 53 of tube 55 and accordingly of the grids of tubes 49, 50, 5| connected thereto. Accordingly the impedance of tubes 49, 50, 5| increases. This has the effect of increasing the voltage drop across the tubes and hence to reduce the voltage at terminal 52 in opposition to the initially assumedtendency of the voltage to increase. Thus, the voltage regulator has the efiect of stabilizing the output voltage across terminals 40 and 52.

The circuit of tubes 49, 50, 5| whereby the grid voltage stabilizes the voltage in the cathode circuit is called a degenerative amplifier type of voltage regulator.

The multiplication of tubes 49, 50, 5| is for the purpose of decreasing the impedance between terminals 38 and 52. The numbercf tubes used may be made one or more as desired.

The number of voltage regulator tubes l1 and 80 may be varied from one to any number needed according to the magnitude of the input voltage and the amplification or the amplifier tubes. It is the function of the amplifier tubes to reduce the number of voltage regulator tubes required.

While there has been described what is at present considered the preferred embodiment of the invention, it will be seen by those skilled in the art within which the present invention resides that various changes and modifications may be 75 made therein without departing from the invention. It is, therefore, intended in the appended claims to cover all changes and modifications that fall within the scope of the invention.

What is claimed is:

1. A direct voltage regulator circuit connected between first and second direct voltage buses, said circuit including first and second potentiometers connected across said buses, a plurality of triodes 10 having cathodes, grids, and plates, the cathodeanode circuits of said triodes being connected in parallel with respect to each other and in series with 'said first bus at a point between said potentiometers, a series circuit from said second bus lit to said; first bus including a plurality of serially connected voltage regulator tubes, a triode having a cathode, a grid, and a plate, a tetrode, said tetrode having a cathode, a. plate, a control grid, and a screen grid with the plate of said tetrode being resistively connected to said first bus and its-cathode being directly connected to the plate or said triode, a resistor connecting the plate of said' triode to the first potentiometer, a direct connection between the grid of said t'riode and said first potentiometer, a resistive connection between the control grid of said tetrode and said second potentiometer, and a direct connection between all the grids of said triodes and the plate of said tetrode.

2. A direct voltage regulator circuit connected between plus and minus buses including a plurality of triodes having cathodes, grids, and plates, the cathode-anode circuits of said triodes being connected in parallel with respect to each other and in series with said plus bus, a first potentiometer on a source side of said triodes between said plus and minus buses, and a series circuit beginning at the minus bus and terminating at the plus bus including a plurality of serially connected voltage regulator tubes and and the anode-cathode connection between said tubes being resistively connected to said first potentiometer, connections between the control elements of said first and second tubes and said first potentiometer, and a direct connection between all the grids of said triodes and the anode of said second tube.

3. A direct voltage regulator circuit as defined in claim 2 which also includes a second potentiometer on a load 'side of said triodes connected between said plus and minus buses, and said second tube is a pentode having a control grid, a screen grid, and a suppressor grid, the control grid of said pentode being resistively connected to said second potentiometer and the screen grid being directly connected to said first potentiometer.

JACK L. BOWERS.

REFERENCES CITED The following references are of recordin the file of this patent:

UNITED STATES PATENTS 7 Number Name Date 2,398,916 Brewer Apr. '23, 1946 2,401,096 Paradise May-28, 1946 2,416,922 Irish Mar. 4, 1947 Lord Apr. 22, 1947 

